In the 3rd Generation Partnership Project (3GPP), a radio access method and a radio network for cellular mobile communication (hereinafter referred to as “Long Term Evolution (LTE)”, or “Evolved Universal Terrestrial Radio Access (EUTRA)”) have been considered. IN LTE, a base station device is also referred to as an evolved NodeB (eNodeB) and a mobile station device is referred to as user equipment (UE). LTE is a cellular communication system in which an area is divided in a cellular pattern into multiple cells, each being served by a base station device. A single base station device may manage multiple cells.
LTE supports Time Division Duplex (TDD). LTE that employs a TDD scheme is also referred to as TD-LTE or LTE TDD. TDD is a technology that enables full duplex communication in a single frequency band by performing time division multiplexing on an uplink signal and a downlink signal.
In the 3GPP, application of a traffic adaptation technology and an interference reduction technology (DL-UL interference management and traffic adaptation) to TD-LTE has been studied. The traffic adaptation technology is a technology that changes a ratio of an uplink resource to a downlink resource according to uplink traffic and downlink traffic. The traffic adaptation technology is also referred to as dynamic TDD.
In NPL 1, a method of using a flexible subframe is disclosed as a method of realizing traffic adaptation. The base station device can perform reception of the uplink signal or transmission of the downlink signal on the flexible subframe. In NPL 1, as long as the base station device does not instruct the mobile station device to transmit the uplink signal on the flexible subframe, the mobile station device regards the flexible subframe as the downlink subframe.
In NPL 1, it is disclosed that hybrid automatic repeat request (HARQ) timing for a PDSCH (physical downlink shared channel) is determined based on newly introduced uplink-downlink configuration, and the HARQ timing for a physical uplink shared channel (PUSCH) is determined based on the first UL-DL configuration.
In NPL 2, it is disclosed that (a) a UL/DL reference configuration is introduced and that (b) several subframes are scheduled, for either of uplink and downlink, by dynamic•grant/assignment from a scheduler.
In Section 7.2 in NPL 3, a procedure that is performed by the mobile station device for reporting of channel state information (CSI) is disclosed. The base station device allocates a downlink resource to the mobile station device, based on the channel state information that is reported from multiple mobile station devices. The channel state information includes a channel quality indicator (CQI).